Go to a local decorative T-shirt outlet and have them silk screen a t-shirt with two hearts pierced by an arrow with a caption written below which reads:

"(Her name),

Will you marry me?

(Your name)"

Present it to her in a gift-wrapped box after returning from an out of town trip, prior to a dinner date.

Hopefully, she'll say "YES" and you can go on to have a great dinner and toast your decision.